Boost Control: Boost Control Solenoid Operation
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Boost Control Solenoid Operation
01.54
| 00:00 | - Before we move on, there are a couple of aspects of the solenoid's operation that are worth discussing in a little detail. |
| 00:08 | The first is the operating frequency or how many cycles per second the solenoid will happily work at. |
| 00:15 | If you drive the solenoid at a frequency that's too slow, the boost will tend to oscillate up and down slightly at the frequency of the solenoid. |
| 00:24 | And this may be accompanied by an audible pulsing of the boost pressure. |
| 00:29 | This obviously isn't desirable and a higher frequency can help eliminate this. |
| 00:35 | If you raise the frequency too high, though, the solenoid won't have enough time to operate properly and it won't work at all. |
| 00:42 | - Somewhere in between is a happy median and most boost solenoids will operate well with a frequency of 15 to 20 hertz. |
| 00:51 | Along with the frequency, there's also a dead band at the high end and low end of the operating duty cycle where the valve essentially won't function. |
| 01:00 | I'll explain this a little more thoroughly. |
| 01:03 | For a popular valve, such as the MAC solenoid, for example, if you provide it with a duty cycle of five percent, the valve won't operate. |
| 01:11 | It's as if the duty cycle is still zero and the valve remains closed. |
| 01:16 | It's not until you get past about 12 to 15 percent duty cycle, that the valve will start operating normally. |
| 01:24 | Likewise, at the high end of the duty cycle, you'll find that anything higher than about 85 to 90 percent, will end up having the valve fully open. |
| 01:33 | So, for the mech valve, the useful range where we actually have control over the boost pressure is approximately 12 to 88 percent. |
| 01:42 | It's important to understand this as it will influence the values we can use in our boost control tuning once we start setting up the system. |
